Add transform to filter arbitrary type fields

[victorandree]

Like FilterRootFields but for arbitrary types, in case you have fields that you do not want to expose. Suggested signature:

export type TypeFieldsFilter = (
  // Or `GraphQLObjectType | GraphQLInputObjectType | GraphQLInterfaceType`
  type: GraphQLNamedType,
  fieldName: string,
  field: GraphQLField<any, any>,
) => boolean;

export default class FilterTypeFields implements Transform {
  constructor(filter: TypeFieldsFilter) {}
}

This should be easy to implement with access to visitSchema (but that's not part of the public interface for this project). Quick implementation for object types. I realized that fields are different on object types, input object types and interfaces, so maybe each should have a separate transform...

import {
  GraphQLField,
  GraphQLFieldConfig,
  GraphQLObjectType,
  GraphQLSchema,
} from 'graphql';
import { Transform } from 'graphql-tools';
import {
  createResolveType,
  fieldToFieldConfig,
} from 'graphql-tools/dist/stitching/schemaRecreation';
import {
  visitSchema,
  VisitSchemaKind,
} from 'graphql-tools/dist/transforms/visitSchema';

export type TypeFieldsFilter = (
  type: GraphQLObjectType,
  fieldName: string,
  field: GraphQLField<any, any>,
) => boolean;

export default class FilterTypeFields implements Transform {
  private filter: TypeFieldsFilter;

  constructor(filter: TypeFieldsFilter) {
    this.filter = filter;
  }

  public transformSchema(originalSchema: GraphQLSchema): GraphQLSchema {
    return visitSchema(originalSchema, {
      [VisitSchemaKind.OBJECT_TYPE]: ((type: GraphQLObjectType) => {
        return filterFields(type, this.filter);
      }) as any,
    });
  }
}

function filterFields(type: GraphQLObjectType, filter: TypeFieldsFilter) {
  const resolveType = createResolveType((_name, originalType) => originalType);
  const fields = type.getFields();
  const newFields = {} as { [key: string]: GraphQLFieldConfig<any, any> };

  Object.keys(fields).forEach(fieldName => {
    const field = fields[fieldName];
    if (filter(type, fieldName, field)) {
      newFields[fieldName] = fieldToFieldConfig(field, resolveType, true);
    }
  });

  return new GraphQLObjectType({
    name: type.name,
    description: type.description,
    astNode: type.astNode,
    fields: newFields,
  });
}

[chollier]

hey @victorandree since you basically have the code ready here, have you thought about making a PR to add the feature to graphql-tools?

[yaacovCR]

Fixed by @orta with #964

[kamilkisiela]

We recently released an alpha version of GraphQL Tools (#1308) that should fix the issue.

Please update graphql-tools to next or run:

npx match-version graphql-tools next

Let us know if it solves the problem, we're counting for your feedback! :)

[yaacovCR]

Folded into #1306